Don't allow title sizes over 255 characters

[mayeaux]

Currently downloads will fail if the title is too long. There should be a hard limit of 255 chars, or whatever the limit would have to be to prevent me getting this error: ERROR: unable to open for writing: [Errno 63] File name too long:

[mayeaux]

Fixed in latest commit

[mayeaux]

This is still bugged if you try to start the download before the title is populated (and thus trimmed)